Network resources that are accessed by computer systems over a computer network include such ubiquitous resources as Websites, file servers, mail servers, and a variety of related services. In dealing with potential malware and other such hazards, a number of technologies have been proposed to categorize the network resources based on their content and other indicia. Such analyses can range from rather superficial examination of names and metadata, to complex and comprehensive assessment of textual, graphical, algorithmic, and multimedia content, as well as links to other resources. The more comprehensive analysis tends to be computationally expensive to process, making it impractical to analyze network resources with a high frequency. One challenge in providing a adequate degree of security from malware or other undesirable content is the fact that network resources are fluid in nature—i.e., subject to frequent updates and changes. A solution is needed that addresses this challenge while providing high-performing categorization of network resource content and associated protection for users accessing such content.